usage.md

How to Use

Basic concepts

The validation process is built around functional options and passing values by specific typed arguments. A common way to use validation is to call the validator.Validate method and pass the argument option with the list of validation constraints.

err := validator.Validate(context.Background(), validation.String("", it.IsNotBlank()))

fmt.Println(err)
// Output:
// violation: This value should not be blank.

List of common validation arguments:

• validation.Nil() - passes result of comparison to nil to test against nil constraints;
• validation.Bool() - passes boolean value;
• validation.NilBool() - passes boolean pointer value;
• validation.Number[T]() - passes generic numeric value;
• validation.NilNumber[T]() - passes generic numeric pointer value;
• validation.String() - passes string value;
• validation.NilString() - passes string pointer value;
• validation.Countable() - passes result of len() to test against constraints based on count of the elements;
• validation.Time() - passes time.Time value;
• validation.NilTime() - passes time.Time pointer value;
• validation.EachNumber[T]() - passes slice of generic numbers to test each of the element against numeric constraints;
• validation.EachString() - passes slice of strings to test each of the element against string constraints;
• validation.Valid() - passes Validatable value to run embedded validation;
• validation.ValidSlice[T]() - passes slice of []Validatable value to run embedded validation on each of the elements;
• validation.ValidMap[T]() - passes map[string]Validatable value to run embedded validation on each of the elements;
• validation.Comparable[T]() - passes generic comparable value to test against comparable constraints;
• validation.NilComparable[T]() - passes generic comparable pointer value to test against comparable constraints;
• validation.Comparables[T]() - passes generic slice of comparable values (can be used to check for uniqueness of the elements);
• validation.Slice[T]() - passes generic slice to test against [SliceConstraint] list (e.g. uniqueness by key via it.HasUniqueValuesBy());
• validation.SliceProperty[T]() - same as [Slice] with property name in violation path;
• validation.Check() - passes result of any boolean expression;
• validation.CheckNoViolations() - passes error to check err for violations, can be used for embedded validation.

For single value validation, you can use shorthand versions of the validation method:

• validator.ValidateBool() - shorthand for validator.Bool();
• validator.ValidateInt() - shorthand for validation.Number[int]();
• validator.ValidateFloat() - shorthand for validation.Number[float64]();
• validator.ValidateString() - shorthand for validation.String();
• validator.ValidateStrings() - shorthand for validation.Comparables[[]string]();
• validator.ValidateCountable() - shorthand for validation.Countable();
• validator.ValidateTime() - shorthand for validation.Time();
• validator.ValidateEachString() - shorthand for validation.EachString();
• validator.ValidateIt() - shorthand for validation.Valid().

See usage examples in the documentation.

How to use the validator

There are two ways to use the validator service. You can build your instance of validator service by using validation.NewValidator() or use singleton service from package github.com/muonsoft/validation/validator.

Example of creating a new instance of the validator service:

// import "github.com/muonsoft/validation"

validator, err := validation.NewValidator(
    validation.DefaultLanguage(language.Russian), // passing default language of translations
    validation.Translations(russian.Messages),    // setting up custom or built-in translations
    validation.SetViolationFactory(userViolationFactory), // if you want to override creation of violations
)

// don't forget to check for errors
if err != nil {
    fmt.Println(err)
}

If you want to use a singleton service make sure to set up your configuration once during the initialization of your application.

// import "github.com/muonsoft/validation/validator"

err := validator.SetUp(
    validation.DefaultLanguage(language.Russian), // passing default language of translations
    validation.Translations(russian.Messages),    // setting up custom or built-in translations
    validation.SetViolationFactory(userViolationFactory), // if you want to override creation of violations
)

// don't forget to check for errors
if err != nil {
    fmt.Println(err)
}